Heat transport device, method of manufacturing a heat transport device, and electronic apparatus

ABSTRACT

A heat transport device includes a working fluid, a capillary member, and a container. The working fluid transports heat by performing a phase change. The capillary member applies a capillary force to the working fluid. The capillary member includes a first mesh member having a mesh of a first size and a second mesh member having a mesh of a second size different from the first size. The second mesh member is folded so that the first mesh member is sandwiched. The container contains the working fluid and the capillary member.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority to Japanese Priority Patent Application JP 2009-238054 filed in the Japan Patent Office on Oct. 15, 2009, the entire content of which is hereby incorporated by reference.

BACKGROUND

The present application relates to a heat transport device that transports heat using a phase change of a working fluid, a method of manufacturing a heat transport device, and an electronic apparatus including a heat transport device.

From the past, as a device that cools a heat source such as a CPU (central processing unit), a flat heat pipe is used. In a heat pipe, a working fluid such as water is contained. The phase change and reflux of a working fluid transports heat, thereby cooling a heat source.

For example, Japanese Patent Application Laid-open No. 2001-183080 discloses a flat heat pipe including a container. In the container, a wick for refluxing a working fluid is provided. The wick is obtained by pressing one band-shaped mesh that is folded a plurality of times. As a result, the wick that is excellent in capillary force is manufactured (paragraph 0014, FIG. 1, etc. of Patent Document 1).

SUMMARY

Incidentally, an electronic apparatus and the like are being increasingly developed to have higher performance. Along with this, a heat generation amount from an electronic apparatus and the like is being increased. Accordingly, a heat transport device having a higher heat transport performance is demanded. To suppress a manufacturing cost, it is desirable to manufacture such a heat transport device having a higher performance at a high yield in a short time.

In view of the above-mentioned circumstances, it is desirable to provide a heat transport device that has a higher heat transport performance and is capable of being manufactured in a short time with good workability, a manufacturing method of the heat transport device, and an electronic apparatus including the heat transport device.

According to an embodiment, there is provided a heat transport device including a working fluid, a capillary member, and a container.

The working fluid transports heat by performing a phase change.

The capillary member applies a capillary force to the working fluid. The capillary member includes a first mesh member having a mesh of a first size and a second mesh member having a mesh of a second size different from the first size. The second mesh member is folded so that the first mesh member is sandwiched.

The container contains the working fluid and the capillary member.

In the heat transport device, by appropriately combining the first and second mesh members whose mesh sizes are different from each other, the heat transport efficiency by the working fluid can be improved. For example, in the case where a plurality of mesh members are layered in the container, it is necessary to position the mesh members. However, the heat transport device of this embodiment, the first mesh member is sandwiched between the second mesh member, and therefore such a positioning is unnecessary, with the result that the workability is improved in forming the heat transport device. As a result, it is possible to manufacture the heat transport device having high heat transport performance in a short time with good workability.

The first mesh member may have an end portion. In this case, the second mesh member may be folded to cover the end portion.

The first and second mesh members are formed by weaving wires. The wires may run in the end portion thereof. For example, in the case where the container is formed by bonding a plurality of members, there is a fear that the run wires may get into the bonding area of the plurality of members, which may cause leakage therefrom. However, in the heat transport device of this embodiment, the second mesh member is folded so as to cover the end portion of the first member. Accordingly, the folded part of the second mesh member is disposed along the bonding area, thereby making it possible to prevent the wires from getting into the bonding area. As a result, the yield in the manufacture of the heat transport device can be improved.

The first mesh member may have a pair of end portions that are opposed to each other. In this case, the second mesh member may be folded to cover the pair of end portions.

In the heat transport device, the second mesh member is folded so as to cover the pair of end portions of the first mesh member, which are opposed to each other. In this way, the way of folding the second mesh member is set as appropriate, with the result that the heat transport device having the high heat transport performance can be manufactured in the short time with good workability.

The first size may be smaller than the second size.

The heat transport device may further include a liquid-phase flow path through which the working fluid in a liquid phase passes and a gas-phase flow path through which the working fluid in a gas phase passes.

In this case, the container may include an internal space having a thickness that is equal to a thickness of the capillary member.

Further, the capillary member may include the first mesh member and the second mesh member. The first mesh member serves as the liquid-phase flow path, and the second mesh member serves as the gas-phase flow path.

In the heat transport device, since the thickness of the internal space of the container is the same as the thickness of the capillary member, the capillary member is provided in the entire internal space of the container. With this structure, the durability of the container can be improved. For example, it is possible to prevent the container from being deformed due to an internal pressure generated by an increase in temperature of the inside of the container. In addition, there is no need to provide, in the internal space, another member for improving the durability of the container, with the result that the heat transport device can be manufactured in the short time with good workability. In the heat transport device of this embodiment, the first mesh member having the smaller meshes is set as the liquid-phase flow path, and the second mesh member having the larger meshes is set as the gas-phase flow path, which can improve the heat transport performance.

The first mesh member and the second mesh member may be alternately folded to be sandwiched therebetween.

In the heat transport device, the first mesh member and the second mesh member are alternately folded so as to be sandwiched therebetween. Such a capillary member is provided, thereby allowing the capillary member to more largely occupy the inside of the container, which can improve the heat transport efficiency.

The container may include a first member and a second member that are bonded to each other.

In this case, the capillary member may be contained in the container so that a folded part of the second mesh member is disposed along a bonding area of the first and second members.

The container may include one plate member that is folded and bonded to form the container.

In this case, the capillary member may be contained in the container so that a folded part of the second mesh member is disposed along a bonding area of the plate member.

In the heat transport device, since the container is formed by folding the one plate member, the number of components can be reduced, and the cost can be saved. In addition, if the container is constituted of a plurality of members, it is necessary predetermined positioning accuracy for the members. In contrast, in this embodiment, the high positioning accuracy is unnecessary. Further, the folded part of the second mesh member is disposed along the bonding area of the plate member, with the result that it is possible to prevent the wires of the first and second mesh members from getting into the bonding area of the plate member.

According to another embodiment, there is provided a heat transport device including a working fluid, a capillary member, and a container.

The working fluid transports heat by performing a phase change.

The capillary member applies a capillary force to the working fluid, and the capillary member includes a first mesh member having meshes arranged in a first direction and a second mesh member having meshes arranged in a second direction different from the first direction. The second mesh member is folded so that the first mesh member is sandwiched.

The container contains the working fluid and the capillary member.

In the heat transport device, by appropriately combining the first and second mesh members whose mesh sizes are different from each other, the heat transport efficiency by the working fluid can be improved.

According to another embodiment, there is provided a method of manufacturing a heat transport device that includes forming a capillary member used for a heat transport device by folding a second mesh member to cause a first mesh member to be sandwiched and cover an end portion of the first mesh member. The first mesh member has a mesh of a first size, and the second mesh member has a mesh of a second size different from the first size.

The capillary member is placed on a first member that constitutes a container of the heat transport device so that a folded part of the second mesh member is disposed along a bonding area of the first member.

The container that contains the capillary member is formed by bonding a second member that constitutes the container to the bonding area of the first member.

According to another embodiment, a method of manufacturing a heat transport device includes forming a capillary member used for a heat transport device by folding a second mesh member to cause a first mesh member to be sandwiched and cover a pair of end portions of the first mesh member.

The capillary member is placed on a first member that constitutes a container of the heat transport device so that a folded part of the second mesh member is disposed along a bonding area of the first member.

The container that contains the capillary member is formed by bonding a second member that constitutes the container to the bonding area of the first member.

By the manufacturing method, the heat transport device can be manufactured in the short time with good workability. Further, by using the first and second mesh members whose mesh sizes are different, the heat transport performance can be improved.

According to another embodiment, there is provided a method of manufacturing a heat transport device including forming a capillary member used for a heat transport device by folding a second mesh member to cause a first mesh member to be sandwiched and cover an end portion of the first mesh member, the first mesh member having a mesh of a first size, the second mesh member having a mesh of a second size different from the first size.

The capillary member is placed on one plate member that constitutes a container of the heat transport device so that a folded part of the second mesh member is disposed along a bonding area of the plate member.

The container that contains the capillary member is formed by folding and bonding the plate member to the bonding area.

According to another embodiment, there is provided an electronic apparatus including a heat source and a heat transport device.

The heat transport device includes a working fluid, a capillary member, and a container.

The working fluid transports heat by performing a phase change.

The capillary member applies a capillary force to the working fluid, and the capillary member includes a first mesh member having a mesh of a first size and a second mesh member having a mesh of a second size different from the first size. The second mesh member is folded so that the first mesh member is sandwiched.

The container is connected to the heat source, and contains the working fluid and the capillary member.

As described above, according to the an embodiment, it is possible to provide the heat transport device that has the high heat transport performance and is capable of being manufactured in the short time with good workability, the method of manufacturing the heat transport device, and the electronic apparatus including the heat transport device.

Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic perspective view showing a heat transport device according to a first embodiment;

FIG. 2 is a cross-sectional view of the heat transport device of FIG. 1, which is taken along a short-side direction (along the line A-A);

FIG. 3 are enlarged plan views of first and second mesh members shown in FIG. 2;

FIG. 4 is a schematic cross-sectional view showing a heat transport device given as a comparative example;

FIG. 5 is a cooling model diagram of a general heat transport device;

FIG. 6 is a schematic cross-sectional view for explaining the operation of the heat transport device according to the first embodiment;

FIG. 7 are partial enlarged views showing mesh members of a capillary member shown in FIG. 4 and the first and second mesh members of the first embodiment in comparison;

FIG. 8 is a diagram showing the heat transport performance of the heat transport device according to the first embodiment and the heat transport performance of the heat transport device shown in FIG. 4 in comparison;

FIG. 9 are diagrams for explaining a method of forming the capillary member provided to the heat transport device according to the first embodiment;

FIG. 10 are diagrams for explaining a method of manufacturing the heat transport device according to the first embodiment;

FIG. 11 is a schematic cross-sectional view showing a heat transport device according to a second embodiment;

FIG. 12 are diagrams for explaining a method of forming a capillary member according to the second embodiment;

FIG. 13 is a schematic cross-sectional view showing a heat transport device according to a third embodiment;

FIG. 14 are plan views showing first and second mesh members according to the third embodiment;

FIG. 15 are enlarged plan views showing the first and second mesh members shown in FIG. 14;

FIG. 16 is a schematic cross-sectional view showing a heat transport device according to a fourth embodiment;

FIG. 17 are diagrams for explaining a method of forming a capillary member according to the fourth embodiment;

FIG. 18 is a schematic cross-sectional view showing a heat transport device according to a fifth embodiment;

FIG. 19 is a schematic exploded perspective view showing the heat transport device according to the fifth embodiment;

FIG. 20 is a schematic cross-sectional view showing a heat transport device according to a sixth embodiment;

FIG. 21 is a schematic cross-sectional view showing a heat transport device according to a seventh embodiment;

FIG. 22 are diagrams for explaining a method of forming a capillary member according to the seventh embodiment;

FIG. 23 is a schematic perspective view showing a heat transport device according to an eighth embodiment;

FIG. 24 are diagrams for explaining a method of manufacturing a heat transport device according to the eighth embodiment;

FIG. 25 is a schematic perspective view showing a heat transport device according to a ninth embodiment;

FIG. 26 are diagrams for explaining a method of forming a capillary member according to the ninth embodiment;

FIG. 27 are diagrams for explaining a method of forming a capillary member as another example in the ninth embodiment;

FIG. 28 is a schematic perspective view showing an electronic apparatus according to a tenth embodiment;

FIG. 29 are diagrams showing a modified example of the heat transport device of FIG. 2 according to the first embodiment; and

FIG. 30 are diagrams showing a modified example of the heat transport device of FIG. 2 according to the first embodiment.

DETAILED DESCRIPTION

Hereinafter, an embodiment will be described with reference to the drawings.

First Embodiment Structure of Heat Transport Device

FIG. 1 is a schematic perspective view showing a heat transport device according to a first embodiment. FIG. 2 is a cross-sectional view of the heat transport device taken along a short-side direction (along the line A-A of FIG. 1). It should be noted that in the figures used for describing the present specification, sizes different from actual sizes may be used for the sake of simplicity.

A heat transport device 100 includes a container 1 having a rectangular thin-plate shape. The container 1 is formed by bonding a dish-shaped lower plate member 3 (first member) and a flat-plate-shaped upper plate member 4 (second member) to each other. The lower plate member 3 has a depressed portion 2. At this time, the depressed portion 2 of the lower plate member 3 corresponds to an internal space 2′ of the container 1.

Typically, the lower plate member 3 and the upper plate member 4 are made of oxygen-free copper, tough pitch copper, or a copper alloy. However, the material is not limited to those, and metal other than copper, a resin, or another material having a higher thermal conductivity may be used as the lower plate member 3 and the upper plate member 4.

Typically, the length of the container 1 in a long-side direction is set to about 10 mm to 500 mm, and the length of the container 1 in a short-side direction is set to about 5 mm to 300 mm. Further, typically, the thickness of the container 1 is set to 0.3 mm to 5 mm. However, the lengths and the thickness of the container 1 are not limited to those values and can be set as appropriate.

The container 1 has an inlet (not shown) whose diameter is about 0.1 mm to 1 mm, for example. Through the inlet, a working fluid is injected into the container 1. Typically, the working fluid is injected in the state where the inside of the container 1 is depressurized. Examples of the working fluid include pure water, alcohol such as ethanol, a fluorine-based liquid such as Fluorinert (registered trademark) FC-72, and a mixture liquid of pure water and alcohol.

As shown in FIG. 2, in the internal space 2′ of the container 1 of the heat transport device 100, a capillary member 5 for causing a capillary force to act on the working fluid is provided. A gap between the capillary member 5 and the upper plate member 4 corresponds to a hollow 6. In this embodiment, a liquid-phase working fluid moves mainly through the capillary member 5, and a gas-phase working fluid moves mainly through the hollow 6. That is, the capillary member 5 serves as a liquid-phase flow path 5′, and the hollow 6 serves as a gas-phase flow path 6′.

The capillary member 5 is constituted of a first mesh member 7 and a second mesh member 8. As shown in FIG. 2, the second mesh member 8 is folded so that the first mesh member 7 is sandwiched, thereby forming the capillary member 5. Accordingly, in a part except a part 9 where the second mesh member 8 is folded, the first and second mesh members 7 and 8 are layered. The folding of the second mesh member 8 will be described in detail in the description of a method of manufacturing the heat transport device 100 below.

FIGS. 3A and 3B are enlarged plan views of the first and second mesh members 7 and 8. FIG. 3A is an enlarged plan view of the first mesh member 7, and FIG. 3B is an enlarged plan view of the second mesh member 8.

As shown in FIG. 3A, the first mesh member 7 includes first wires 10 and second wires 11. The first wires 10 are extended in the long-side direction of the heat transport device 100, and the second wires 11 are extended in the short-side direction of the heat transport device 100. The first and second wires 10 and 11 are alternately woven, thereby forming the first mesh member 7 having a plurality of meshes 12.

As shown in FIG. 3B, the second mesh member 8 includes first wires 13 and second wires 14. The first wires 13 are extended in the long-side direction of the heat transport device 100, and the second wires 14 are extended in the short-side direction of the heat transport device 100. The first and second wires 13 and 14 are alternately woven, thereby forming the second mesh member 8 having a plurality of meshes 15.

As the wires that form the first and second mesh members 7 and 8, metal thin wires made of copper, phosphor bronze, aluminum, silver, stainless steel, molybdenum, or an alloy thereof are used, for example. In addition, examples of the way of weaving the first and second wires 10 and 11 and the way of weaving the first and second wires 13 and 14 include a plain weave, a trill weave, a lock crimp weave, or a flat top weave.

As shown in FIGS. 3A and 3B, a size W₁ (first size) of the meshes 12 of the first mesh member 7 is set to be smaller than a size W₂ (second size) of the meshes 15 of the second mesh member 8. That is, in this embodiment, a mesh number of the first mesh member 7 is larger than that of the second mesh member 8.

Here, the “mesh number” refers to the number of meshes per inch of the mesh members. Therefore, the mesh member having a larger mesh number has a larger number of meshes per inch. That is, the size of the mesh thereof is smaller. In the following description, the mesh member whose mesh number is 100 is referred to as the mesh member of #100.

In this embodiment, the first mesh member 7 of #150 and the second mesh member 8 of #100 are used. However, the combination of the mesh numbers is not limited to the above example. For example, the first mesh member 7 of #200 and the second mesh member 8 of #150 may be used. The combination of the mesh numbers can be set as appropriate within a range in which the mesh number of the first mesh member 7 is larger than that of the second mesh member 8.

Operation of General Heat Transport Device

FIG. 4 is a schematic cross-sectional view showing a heat transport device given as a comparative example. FIG. 4 shows the cross-sectional view in the case where a heat transport device 980 is taken along a long-side direction.

The heat transport device 980 includes a container 981. In the container 981, a capillary member 985 and a working fluid (not shown) are provided. As shown in FIG. 4, the capillary member 985 is bonded to a lower plate member 983 of the container 981 and serves as a liquid-phase flow path 985′. In addition, a hollow 986 formed between the capillary member 985 and an upper plate member 984 of the container 981 serves as a gas-phase flow path 986′.

The capillary member 985 has the structure in which three mesh members 987 having the same mesh number are stacked. The mesh members 987 each are formed by alternately weaving first wires (not shown) and second wires (not shown). The first wires are extended in a long-side direction of the heat transport device 980, and the second wire is extended in a short-side direction thereof. Since the mesh members 987 having the same mesh number are stacked, the sizes of the meshes of the mesh members 987 are the same.

As shown in FIG. 4, in one end portion 995 a of the heat transport device 980 in the long-side direction, an evaporation area E is provided, and in the other end portion 995 b, a condensation area C is provided. A heat source 999 such as a CPU is brought into contact with the evaporation area E on the lower plate member 983 side.

FIG. 5 is a cooling model diagram of a heat transport device. A working fluid in the liquid phase receives heat from the heat source 999 in the evaporation area E and evaporates at a vapor pressure difference ΔPe, to change into the gas phase. The gas-phase working fluid passes through the gas-phase flow path 986′, and moves from the evaporation area E to the condensation area C. At this time, the gas-phase working fluid moves to the condensation area C while receiving a pressure loss ΔPv due to the resistance of the gas-phase flow path 986′.

The gas-phase working fluid that has moved to the condensation area C radiates heat W to condense, and thus changes from the gas phase to the liquid phase. The vapor pressure difference at this time is represented by ΔPc. The liquid-phase working fluid flows through the liquid-phase flow path 985′ by using a capillary force ΔPcap of the capillary member 985 as a pump force to move from the condensation area C to the evaporation area E. At this time, the liquid-phase working fluid moves to the evaporation area E while receiving a pressure loss ΔPl due to the resistance of the liquid-phase flow path 985′.

The liquid-phase working fluid that has returned to the evaporation area E evaporates by receiving the heat from the heat source 999 again. By repeating the operations described above, the heat from the heat source 999 is transported.

In the case where the total pressure loss in the heat transport device 980 is smaller than the capillary force ΔPcap of the capillary member 985, the heat transport device 980 operates properly. In contrast, in the case where the total pressure loss in the heat transport device 980 is larger than the capillary force ΔPcap of the capillary member 985, the heat transport device 980 does not operate, and the heat is not transported. When there is a balance between the total pressure loss and the capillary force ΔPcap, a maximum heat transport amount Qmax of the heat transport device 980 is obtained.

Accordingly, ΔPcap at the time when the maximum heat transport amount Qmax is obtained is expressed by the following expression (1):

ΔPcap=ΔPv+ΔPl+ΔPe+ΔPc+ΔPh  (1)

where ΔPv represents the pressure loss of the gas-phase working fluid, ΔPl represents the pressure loss of the liquid-phase working fluid, ΔPe represents the pressure difference due to the evaporation, ΔPc represents the pressure difference due to the condensation, and ΔPh represents the pressure difference due to a volume force.

Herein, the maximum heat transport amount Qmax is expressed by the following expression (2):

Qmax=ΔPcap/Rq  (2)

where Rq represents a flow path resistance per unit heat amount.

In addition, the maximum heat transport amount Qmax is expressed by the following expression (3):

Qmax=ΔPcap*H/Rtotal  (3)

where H represents a latent heat and Rtotal represents the total flow path resistance.

The total flow path resistance Rtotal is the sum of a resistance Rv of the gas-phase flow path, a resistance Rl of the liquid-phase flow path, an evaporation resistance Re, a condensation resistance Rc, and a resistance due to a volume force Rb. Accordingly, on the basis of the expression (3), the maximum heat transport amount Qmax is generally increased as the capillary force ΔPcap becomes larger, and the maximum heat transport amount Qmax is decreased as the resistance Rl of the liquid flow path becomes larger.

The pressure loss ΔPv of the gas-phase working fluid, the pressure loss ΔPl of the liquid-phase working fluid, the pressure difference ΔPe due to the evaporation, the pressure difference ΔPc of the condensation, and the pressure difference ΔPh due to the volume force Rb are expressed by the following expressions (4) to (8), respectively:

ΔPv=8*μv*Q*L/(π*ρv*rV̂4*H)  (4)

ΔPl=μl*Q*L/(K*Aw*ρl*H)  (5)

ΔPe=(RT/2π)̂(1/2)*Q/[αc(H−1/2*RT)*rv*le]  (6)

ΔPc=(RT/2π)̂(1/2)*Q/[αc(H−1/2*RT)*rv*lc]  (7)

ΔPh=(ρl−ρv)*g*L*sin φ  (8)

where μv represents a viscosity coefficient of the gas-phase working fluid, μl represents a viscosity coefficient of the liquid-phase working fluid, ρv represents a density of the gas-phase working fluid, ρl represents a density of the liquid-phase working fluid, Q represents the heat transport amount, L represents the length of the heat transport device 980 in the long-side direction, le represents a length of the evaporation area E in the long-side direction, lc represents a length of the condensation area C in the long-side direction, Aw represents a cross-sectional area of a mesh member, rv represents a capillary radius of the gas-phase flow path 986′, K represents an osmotic coefficient, R represents a gas constant, g represents a gravity acceleration, and y represents an inclination of the heat transport device 980 with respect to a horizontal line (the volume force Rb is 0 in the case where the heat transport device 980 is used horizontally).

When an attention is focused on the expressions (4), (6), and (7) out of the expressions (4) to (8), it is found that the pressure loss ΔPv of the gas-phase working fluid, the pressure difference ΔPe due to the evaporation, and the pressure difference ΔPc due to the condensation are functions of the capillary radius rv of the gas-phase flow path 986′. The capillary radius rv of the gas-phase flow path 986′ are put as denominators in the expressions (4), (6), and (7). Therefore, by increasing the capillary radius iv of the gas-phase flow path 986′, the three pressure losses ΔPv, ΔPe, and ΔPc can be reduced, with the result that the maximum heat transport amount Qmax can be increased.

Here, a description will be given on a capillary radius r of a flow path through which the gas-phase or liquid-phase working fluid is moved. In the case where a mesh member obtained by weaving wires is used as the flow path of the working fluid, the capillary radius r is expressed by the following expression (9):

r=(W+D)/2  (9)

where W represents the size of the meshes of the mesh member, and D represents the diameter of the wires.

On the other hand, for example, in the case where the mesh member or the like is not used as the flow path of the working fluid, and a rectangular hollow functions as the flow path, the capillary radius r is expressed by the following expression (10):

r=ab/(a+b)  (10)

where a represents the width of the flow path (length in the short-side direction), and b represents the depth of the flow path (thickness of the flow path).

Operation of Heat Transport Device 100

Next, the operation of the heat transport device 100 according to this embodiment will be described. FIG. 6 is a schematic cross-sectional view for explaining the operation of the heat transport device. FIG. 6 shows the cross section in the case where the heat transport device 100 is taken along the long-side direction. Therefore, in FIG. 6, the folded part of the second mesh member 8 is not shown.

As shown in FIG. 6, in one end portion 15 a of the heat transport device 100 in the long-side direction, the evaporation area E is provided, and in the other end portion 15 b, the condensation area C is provided. The heat source 999 such as a CPU is brought into contact with the evaporation area E on the lower plate member 3 side. The heat source 999 may be in contact with the evaporation area E on the upper plate member 4 side.

A working fluid in the liquid phase receives heat from the heat source 999 in the evaporation area E, and evaporates at the vapor pressure difference ΔPe, to change into the gas phase. The gas-phase working fluid passes through the gas-phase flow path 6′ and moves from the evaporation area E to the condensation area C. At this time, the gas-phase working fluid moves to the condensation area C while receiving the pressure loss ΔPv due to the resistance of the gas-phase flow path 6′.

The gas-phase working fluid that has moved to the condensation area C radiates heat W to condense, and thus changes from the gas phase to the liquid phase. The vapor pressure difference at this time is represented by ΔPc. The liquid-phase working fluid flows through the liquid-phase flow path 5′ by using the capillary force ΔPcap of the capillary member 5 as the pump force to move from the condensation area C to the evaporation area E. At this time, the liquid-phase working fluid moves to the evaporation area E while receiving the pressure loss ΔPl due to the resistance of the liquid-phase flow path 5′.

The liquid-phase working fluid that has returned to the evaporation area E evaporates by receiving the heat from the heat source 999 again. By repeating the operations described above, the heat from the heat source 999 is transported.

Here, an attention is focused on the capillary member 5 according to this embodiment. As described above, the capillary member 5 of this embodiment has the structure in which the first and second mesh members 7 and 8 are layered in a part except the part 9 where the second mesh member 8 is folded.

As described above, on the basis of the expression (3), the maximum heat transport amount Qmax is increased as the capillary force ΔPcap becomes larger, and is decreased as the resistance Rl of the liquid-phase flow path becomes larger. For example, in the case where the mesh member is used as the capillary member, by increasing the size of the meshes of the mesh member, the resistance Rl of the liquid-phase flow path can be reduced. However, if the size of the mesh of the mesh member is increased, the capillary force ΔPcap is decreased.

In this embodiment, the size W1 of the meshes 12 of the first mesh member 7 is set to be smaller than the size W2 of the meshes 15 of the second mesh member 8. That is, the proper capillary force ΔPcap is secured by the first mesh member 7 having the smaller meshes while reducing the resistance Rl of the liquid-phase flow path by the second mesh member 8 having the larger meshes. As a result, heat transport efficiency by the working fluid is improved.

Further, the liquid-phase working fluid mainly passes through the capillary member 5 serving as the liquid-phase flow path 5′, and the gas-phase working fluid mainly passes through the hollow 6 serving as the gas-phase flow path 6′. However, in some cases, the gas-phase working fluid moves through the capillary member 5. In particular, the folded part of the second mesh member 8 on the upper plate 4 side is a part through which the gas-phase and liquid-phase working fluids pass.

If the capillary member 5 is regarded as the gas-phase flow path of the working fluid, on the basis of the expression (9), the capillary radius rv is defined by the sizes W1 and W2 of the meshes 12 and 15 of the first and second mesh members 7 and 8, respectively, and the diameters of the wires of the first and second mesh members 7 and 8. Therefore, by using the second mesh member 8 having the larger meshes as the capillary member 5, the capillary radius rv of the gas-phase flow path is increased, and the three pressure losses ΔPv, ΔPe, and ΔPc are reduced on the basis of the expressions (4), (6), and (7). Thus, the maximum heat transport amount Qmax can be increased, with the result that the heat transport efficiency of the heat transport device 100 is improved.

As shown in FIG. 6, the capillary member 5 is bonded to the lower plate member 3. If the size of the meshes of the capillary member 5 is set to be too small in order to obtain a larger capillary force ΔPcap, the meshes may be collapsed due to the bonding to the lower plate member 3. In this embodiment, however, the second mesh member 8 having the larger meshes is bonded to the lower plate member 3. Therefore, it is possible to prevent such a problem.

FIGS. 7A and 7B are partial enlarged views showing the mesh members 987 of the capillary member 985 shown in FIG. 4 and the first and second mesh members 7 and 8 of this embodiment in comparison. FIG. 7A shows the mesh members 987 of the heat transport device 980, and FIG. 7B shows the first and second mesh members 7 and 8 of this embodiment.

As shown in FIG. 7A, in the capillary member 985, the mesh members 987 having the same mesh number are layered, so the meshes of the mesh members 987 are overlapped with each other. Therefore, a gap through which the liquid-phase working fluid moves is not secured, which increases the resistance of the flow path and makes it difficult to apply the appropriate capillary force ΔPcap to the liquid-phase working fluid.

On the other hand, as shown in FIG. 7B, the first and second mesh members 7 and 8 of this embodiment have the different mesh numbers from each other, which can prevent the meshes of the first mesh member 7 and the meshes of the second mesh member 8 from being overlapped with each other. Thus, the resistance of the flow path with respect to the liquid-phase working fluid can be reduced, and the appropriate capillary force ΔPcap can be applied to the liquid-phase working fluid. As a result, it is possible to improve the heat transport performance of the heat transport device 100.

FIG. 8 is a diagram showing the heat transport performance of the heat transport device 100 and the heat transport performance of the heat transport device 980 shown in FIG. 4 in comparison. Here, for the capillary member 985 of the heat transport device 980, the three mesh members 987 of #100 are used. The maximum heat transport amount Qmax of each of the heat transport device 980 and the heat transport device 100 of this embodiment are measured.

As described above, the capillary member 5 according to this embodiment is formed by folding the second mesh member 8 of #100 so that the first mesh member 7 of #150 is sandwiched. On the other hand, the capillary member 985 of the heat transport device 980 has the structure in which the three mesh members of #100 are stacked. As shown in FIG. 8, the maximum heat transport amount Qmax of the heat transport device 100 of this embodiment is larger than the maximum heat transport amount Qmax of the heat transport device 980.

(Method of Manufacturing Heat Transport Device)

FIGS. 9A to 9C are diagrams for explaining a method of forming the capillary member 5 provided to the heat transport device 100 according to this embodiment. As shown in FIG. 9A, the second mesh member 8 is prepared. The second mesh member 8 is nearly twice as large as the internal space 2′ of the container 1 when viewed from above. The second mesh member 8 has a right-side area R₂, a left-side area L₂, and a pair of end portions 16 a and 16 b. The end portions 16 a and 16 b are opposed to each other in a direction in which the right-side area R₂ and the left-side area L₂ are arranged.

As shown in FIG. 9B, on the right-side area R2 of the second mesh member 8, the first mesh member 7 formed into a shape that is almost the same as the shape of the internal space 2′ is placed. The first mesh member 7 has a pair of end portions 17 a and 17 b opposed to each other in the short-side direction. As shown in FIG. 9B, the end portion 17 b is aligned with the end portion 16 b of the second mesh member 8. The end portion 17 a of the first mesh member 7 is placed on approximately the center of the second mesh member 8.

The first mesh member 7 is cut into a predetermined shape from a mesh sheet of #150. The second mesh member 8 is cut into a predetermined shape from a mesh sheet of #100. For cutting the first and second mesh members 7 and 8 out of the mesh sheets, a laser cutter, a cutting die, or the like is used. Alternatively, a wire electric discharge machining (wire cut) may be used.

As shown in FIG. 9C, the second mesh member 8 is folded so that the first mesh member 7 is sandwiched. Thus, the first mesh member 7 is sandwiched between the right-side area R2 and the left-side area L2 of the second mesh member 8. In addition, the end portion 17 a of the first mesh member 7 is covered with the part 9 at which the second mesh member 8 is folded. The end portion 16 a of the second mesh member 8 is aligned with the end portion 17 b of the first mesh member 7 and the end portion 16 b of the second mesh member 8. The second mesh member 8 may be manually folded or may be folded by a processing machine such as a folding machine.

In this way, the capillary member 5 having almost the same shape as the internal space 2′ of the container 1 is formed. A long-side direction of the capillary member 5 shown in FIG. 9C corresponds to the long-side direction of the container 1, and a short-side direction of the capillary member 5 corresponds to the short-side direction of the container 1.

FIGS. 10A and 10B are diagrams for explaining the method of manufacturing the heat transport device 100. FIG. 10 shows the cross section in the case where the heat transport device 100 to be formed is taken along the short-side direction.

As shown in FIG. 10A, the capillary member 5 is placed in the depressed portion 2 of the lower plate member 3 so that the folded part 9 of the second mesh member 8 is disposed along a side wall 18 that surrounds the depressed portion 2 of the lower plate member 3.

For example, in the heat transport device 980 shown in FIG. 4, the mesh members 987 have to be layered while being positioned with high accuracy. In contrast, in this embodiment, since the capillary member 5 formed by the process shown in FIGS. 9A to 9C is placed in the depressed portion 2 of the lower plate member 3. Therefore, the positioning as described above does not have to be performed. As a result, it is possible to manufacture the heat transport device 100 having the high heat transport performance in a short time with good workability.

To prevent impurities from getting into the container, the capillary member may be washed before being placed in the container in some cases. In this case, in the heat transport device 980, the mesh members 987 have to be washed one by one. In contrast, in this embodiment, the capillary member 5 formed by the process shown in FIG. 9 can be washed at a time, with the result that the workability in assembling the heat transport device 100 can be improved.

Further, in the heat transport device 980 shown in FIG. 4, the three mesh members 987 are used for forming the capillary member 985. In contrast, in this embodiment, the first and second mesh members 7 and 8 form the capillary member 5. That is, in this embodiment, the number of mesh members used can be reduced, with the result that a cutting cost of the mesh members can be saved.

As shown in FIG. 10B, the upper plate member 4 is bonded onto the side wall 18 of the lower plate member 3. That is, in this embodiment, the upper surface of the side wall 18 of the lower plate member 3 corresponds to a bonding area S, and the folded part 9 of the second mesh member 8 is disposed along the bonding area S. In FIG. 10B, the depressed portion 2 of the lower plate member 3 is shown in a visually understandable manner. But, actually, the height of the side wall 18 corresponding to the thickness of the container 1 is significantly small, specifically, 0.3 mm to 5 mm, for example. Thus, substantially, the folded part 9 of the second mesh member 8 is disposed along the bonding area S.

As the method of bonding the lower plate member 3 and the upper plate member 4, a diffusion bonding, an ultrasonic bonding, a brazing, a welding, or the like may be used. In the case where the diffusion bonding is performed on the lower plate member 3 and the upper plate member 4, by a temperature and a pressure due to the diffusion bonding, the capillary member 5 and the lower plate member 3 may be bonded with each other. Alternatively, in a process separated from the bonding process of the lower plate member 3 and the upper plate member 4, the capillary member 5 and the lower plate member 3 may be bonded by the bonding method as described above.

The first and second mesh members 7 and 8 are formed by weaving the wires made of metal thin wires. Therefore, there is a fear that the wire may run in the end portions of the first and second mesh members 7 and 8. If the run wire gets into the bonding area S of the lower plate member 3, and the wire is sandwiched between the lower plate member 3 and the upper plate member 4, leakage may be caused from the part where the wire is sandwiched. In contrast, in this embodiment, in the heat transport device 100, the second mesh member 8 is bonded so that the end portion 17 a of the first mesh member 7 is covered. Then, the folded part 9 of the second mesh member 8 is disposed along the bonding area S of the lower plate member 3. Therefore, it is possible to prevent the wires of the first and second mesh members 7 and 8 from getting into the bonding area S in the area where the folded part 9 of the second mesh member 8 is disposed. As a result, the yield in the manufacture of the heat transport device 100 can be improved.

Second Embodiment

A description will be given on a heat transport device according to a second embodiment. In the following description, the structures and actions that are the same as those of the heat transport device 100 that are described in the first embodiment will be denoted by the same reference numerals and symbols, and their descriptions will be omitted.

FIG. 11 is a schematic cross-sectional view showing a heat transport device according to the second embodiment. FIGS. 12A and 12B are diagrams for explaining a method of forming a capillary member of this embodiment. FIG. 11 shows the cross-sectional view in the case where the heat transport device of this embodiment is taken along a short-side direction.

As shown in FIG. 11, a heat transport device 200 of this embodiment includes a capillary member 205 whose structure is different from the capillary member 5 of the first embodiment. The capillary member 205 of this embodiment includes a first mesh member 207 having smaller meshes and a second mesh member 208 having larger meshes. The second mesh member 208 is folded so that the first mesh member 207 is sandwiched, thereby forming the capillary member 205. Hereinafter, the method of forming the capillary member 205 of this embodiment will be described.

As shown in FIG. 12A, the mesh member 208 is prepared. The second mesh member 208 is nearly twice as large as the internal space 2′ of the container 1 when viewed from above. The second mesh member 208 has three areas of the right-side area R₂, the left-side area L₂, and a central area C₂. Further, the second mesh member 208 has a pair of end portions 216 a and 216 b. The end portions 216 a and 216 b are opposed to each other in a direction in which the three areas are arranged. In the central area C₂ of the second mesh member 208, the first mesh member 207 formed into a shape that is almost the same as the shape of the internal space 2′ is placed. The first mesh member 207 has a pair of end portions 217 a and 217 b opposed to each other in the short-side direction. As shown in FIG. 12A, the pair of end portions 217 a and 217 b of the first mesh member 207 is placed in the central area C₂ of the second mesh member 208.

As shown in FIG. 12B, the second mesh member 208 is folded so that the first mesh member 207 is sandwiched. The first mesh member 207 is sandwiched between the central area C₂ and the left-side area L₂ of the second mesh member 208 and between the central area C₂ and the right-side area R₂ thereof. Therefore, the pair of end portions 217 a and 217 b of the first mesh member 207 is covered with folded parts 209 a and 209 b of the second mesh member 208. The pair of end portions 216 a and 216 b of the second mesh member 208 is disposed so as to be opposed to each other in approximately the center of the first mesh member 207. Thus, the capillary member 205 of this embodiment is formed.

As shown in FIG. 11, the capillary member 205 formed is placed in the depressed portion 2 of the lower plate member 3, and the lower plate member 3 and the upper plate member 4 are bonded in the bonding area S on the side wall 18 of the lower plate member 3. The capillary member 205 is placed in the depressed portion 2 of the lower plate member 3 so that the folded parts 209 a and 209 b of the second mesh member 208 are disposed along the bonding area S. Thus, the heat transport device 200 of this embodiment is manufactured.

In this embodiment, the folded parts 209 a and 209 b of the second mesh member 208 are disposed along the bonding area S in the long-side direction of the container 1. Therefore, it is possible to prevent the wires of the first and second mesh members 207 and 208 from getting into the bonding area S in the long-side direction of the container 1. As a result, the yield in the manufacture of the heat transport device 200 can be improved. As described above, by setting the folding manner of the second mesh member 208 as appropriate, the heat transport device 200 having the high heat transport performance can be manufactured in a short time with good workability.

Further, by increasing a distance between the end portions 216 a and 216 b of the second mesh member 208 which are opposed to each other in approximately the center of the first mesh member 207, the gas-phase flow path 6′ may occupy a larger part of the internal space 2′ of the container 1. By setting the area of the second mesh member 208 prepared in the process shown in FIG. 11A as appropriate, the distance between the end portions 216 a and 216 b after the folding can be appropriately set. When the distance between the end portions 216 a and 216 b are appropriately set, and the ratio between the gas-phase flow path 6′ and the liquid-phase flow path 5′ in the internal space 2′ is appropriately set, the heat transport efficiency of the heat transport device 200 can be improved.

In addition, in the heat transport device 980 shown in FIG. 4, it is necessary to prevent the wire of the mesh member 987 from getting into the bonding area S when the capillary member 985 is provided in the internal space 982′ of the container 981. Therefore, for each mesh member 987, it is necessary to conduct an operation of removing the run wire or an operation of checking whether the wire gets into the bonding area S of the lower member 983, for example. Further, in some cases, the areas of the mesh members 987 are set to be smaller than the area of the internal space 982′ when viewed from above, and the mesh members 987 and the bonding area S (side wall 998) are separated, thereby preventing the wire from getting into the bonding area S.

In contrast, in this embodiment, since the folded parts 209 a and 209 b of the second mesh member 208 are disposed along the bonding area S, the operations as described above are unnecessary, which improves the workability in the manufacture of the heat transport device 200. Further, since there is no need to set the area of the capillary member 5 to be smaller than the size of the internal space 2′ when viewed from above, the capillary member 205 is allowed to occupy the larger part in the inside area 2′. Thus, a high capillary force can be applied to the working fluid, and the heat transport efficiency of the heat transport device 200 can be improved. Further, in this embodiment, even in the case where the area of the capillary member 205 is slightly larger than the size of the internal space 2′ when viewed from above, the capillary member 205 having elasticity can be pushed into the depressed portion 2 of the lower plate member 3. Accordingly, a dimensional tolerance of the area of the capillary member 205 can be increased, with the result that the workability in forming the capillary member 205 can be improved.

In this embodiment, the capillary member 205 is placed in the depressed portion 2 of the lower plate member 3. Alternatively, the capillary member 205 may be placed on a flat lower plate member, and an upper plate member having a depressed portion may be bonded to the bonding area of the lower plate member. In this case, the capillary member 205 is placed on the lower plate member so that the folded parts 209 a and 209 b of the second mesh member 208 are disposed along the bonding area of the lower plate member. Further, the container 1 may be formed of the flat lower plate member, the upper plate member, and a frame member that constitute the side wall of the container 1. The container 1 is formed by bonding the frame member to the bonding area of the lower plate member and bonding the upper plate member to the bonding area of the frame member. In this case, the capillary member 205 is placed on the lower plate member so that the folded parts 209 a and 209 b of the second mesh member 208 are disposed along the bonding area of the lower plate member. Alternatively, after the lower plate member is bonded to the frame member, the capillary member 205 may be placed on the lower plate member so that the folded parts 209 a and 209 b are disposed along the bonding area of the frame member.

Further, in this embodiment, the folded parts 209 a and 209 b of the second mesh member 208 are disposed in the long-side direction of the container 1. The area of the bonding area S of the lower plate member 3 in the long-side direction of the container 1 is larger than that in the short-side direction thereof. Accordingly, when the folded parts 209 a and 209 b of the second mesh member 208 are disposed in the long-side direction of the container 1, the effect as described above becomes larger. However, the second mesh member 208 may be folded so as to correspond to the short-side direction of the container 1, and the folded parts of the second mesh member 208 may be disposed in the short-side direction of the container 1.

Third Embodiment

FIG. 13 is a schematic cross-sectional view showing a heat transport device according to a third embodiment. FIG. 11 shows the cross-sectional view in the case where the heat transport device of this embodiment is taken along a short-side direction.

In a heat transport device 300 of this embodiment, mesh members having the same mesh number are used as first and second mesh members 307 and 308. The second mesh member 308 is folded so that the first mesh member 307 is sandwiched, thereby forming a capillary member 305. At this time, the meshes of the first mesh member 307 and the meshes of the second mesh member 308 are set so as to be arranged in different directions from each other. The folding manner of the second mesh member 308 is the same as that of the second mesh member 208 described in the second embodiment.

FIGS. 14A and 14B are plan views showing the first and second mesh members 307 and 308 of this embodiment. FIGS. 15A and 15B are enlarged plan views showing the first and second mesh members 307 and 308 shown in FIG. 14. FIGS. 14A and 15A show the second mesh member 308, and FIGS. 14B and 15B show the first mesh member 307.

As shown in FIG. 14A, the second mesh member 308 is nearly twice as large as the internal space 2′ when viewed from above. The second mesh member 308 has a plurality of first wires 313 and a plurality of second wires 314, which are woven in a direction approximately perpendicular to the first wires 313. A direction in which the first wires 313 are extended corresponds to the long-side direction of the container 1, and a direction in which the second wires 314 are extended corresponds to the short-side direction of the container 1. Thus, as shown in FIGS. 14A and 15A, meshes 315 of the second mesh member 308 are arranged in the long-side direction and in the short-side direction of the container 1.

As shown in FIG. 14B, the first mesh member 307 is formed into a shape that is almost the same as the shape of the internal space 2′ of the container 1. The first mesh member 307 has a pair of end portions 317 a and 317 b opposed to each other in the short-side direction. A direction in which the pair of end portions 317 a and 317 b corresponds to the long-side direction of the container 1.

In this embodiment, the first mesh member 307 also has the plurality of first wires 313 and the plurality of second wires 314 that are woven in the direction perpendicular to the first wires 313. However, as shown in FIGS. 14B and 15B, in the first mesh member 307, the extended directions of the first and second wires 313 and 314 are set to be different from the extended direction of the pair of end portions 317 a and 317 b. Accordingly, the extended directions of the first and second wires 313 and 314 of the first mesh member 307 are different from those of the first and second wires 313 and 314 of the second mesh member 308. Thus, a direction in which meshes 312 of the first mesh member 307 are arranged is set to be different from the direction in which the meshes 315 of the second mesh member 308 are arranged.

The first and second mesh members 307 and 308 are cut out of a mesh sheet in which the first and second wires 313 and 314 are alternately woven. The second mesh member 308 is cut along the extended directions of the first and second wires 313 and 314. The first mesh member 307 is cut in different directions from the extended directions of the first and second wires 313 and 314. As described above, in this embodiment, two mesh sheets having different mesh numbers do not have to be prepared, which can save a cost of the mesh sheet.

In the capillary member 305 of this embodiment, since the meshes (meshes 312 and 315) of the first and second mesh members 307 and 308 are arranged in the different directions, it is possible to prevent the meshes 312 and 315 from overlapping with each other. Thus, the resistance of the flow path with respect to the liquid-phase working fluid can be reduced, and the high capillary force can be applied to the liquid-phase working fluid. As a result, the heat transport performance of the heat transport device 300 can be improved.

As shown in FIG. 15B, a difference between the direction in which the meshes 312 of the first mesh member 307 are arranged and the direction in which the meshes 315 of the second mesh member 308 are arranged is represented by an angle θ. For example, when the angle θ is set within the range of 5 to 85 degrees, the heat transport performance of the heat transport device 300 can be improved as described above. When the angle θ is set to 90 degrees, the meshes 312 of the first mesh member 307 and the meshes 315 of the second mesh member 308 are probably overlapped with each other. However, there are variations in the weaving form of the first and second wires 313 and 314, so the meshes 312 and 315 may not be overlapped in some cases, even in the case where the angle θ is 90 degrees. Accordingly, it is possible to improve the heat transport performance of the heat transport device 300 even in the case where the angle θ is 90 degrees, so the range of 85 to 90 degrees can also be selected as the angle θ.

It should be noted that in this embodiment, both the first and second mesh members 307 and 308 are formed of the first and second wires 313 and 314 but are not limited to this. In addition, even if the first and second mesh members having different mesh numbers are used, and the directions in which the meshes of the mesh members are set to be different, the heat transport performance of the heat transport device can also be improved.

Fourth Embodiment

FIG. 16 is a schematic cross-sectional view showing a heat transport device according to a fourth embodiment. FIGS. 17A to 17C are diagrams for explaining a method of forming a capillary member of this embodiment. FIG. 16 shows the cross-sectional view in the case where the heat transport device of this embodiment is taken along a short-side direction.

A capillary member 405 of a heat transport device 400 of this embodiment is formed by alternately folding a first mesh member 407 and a second mesh member 408 so as to be sandwiched therebetween. Hereinafter, the method of forming the capillary member 405 of this embodiment will be described.

As shown in FIG. 17A, the first and second mesh members 407 and 408 are prepared. The first and second mesh members 407 and 408 each are nearly twice as large as the internal space 2′ when viewed from above. On the left-side area L₂ of the second mesh member 408 shown in FIG. 17A, a right-side area R₁ of the first mesh member 407 is placed. The first mesh member 407 has a pair of end portions 417 a and 417 b. The end portions 417 a and 417 b are opposed to each other in a direction in which the right-side area R₁ and a left-side area L₁ are arranged. The end portion 417 b is disposed in approximately the center of the second mesh member 408.

As shown in FIG. 17B, the second mesh member 408 is folded so as to cover the end portion 417 b of the first mesh member 407. The end portion 417 b of the first mesh member 407 is covered with a folded part 409 b of the second mesh member 408. Further, the right-side area R₁ of the first mesh member 407 is sandwiched between the left-side area L₂ and the right-side area R₂ of the second mesh member 408. Thus, an end portion 416 b of the second mesh member 408 is disposed in approximately the center of the first mesh member 407.

As shown in FIG. 17C, the first mesh member 407 is folded so as to cover an end portion 416 b of the second mesh member 408. The end portion 416 b of the second mesh member 408 is covered with a folded part 409 a of the first mesh member 407. Further, the right-side area R₂ of the second mesh member 408 is sandwiched between the right-side area R₁ and the left-side area L₁. In this way, the first and second mesh members 407 and 408 are alternately folded so as to be sandwiched therebetween, thereby forming the capillary member 405 of this embodiment. The folded parts 409 a and 409 b of the first and second mesh members 407 and 408 are parts corresponding to the long-side directions of the container 1.

As in this embodiment, by alternately folding the first and second mesh members 407 and 408 so as to be sandwiched therebetween, the number of first and second mesh members 407 and 408 stacked that constitute the capillary member 405 can be increased. Accordingly, the capillary member 405 is allowed to occupy the larger part of the internal space 2′ of the container 1, with the result that the heat transport performance of the heat transport device 400 can be improved.

It should be noted that, as shown in FIG. 16, the end portion 416 a (end portion opposed to the end portion 416 b) of the left-side area L₂ of the second mesh member 408 bonded to the lower plate member 3 is disposed on an inner side of the container 1 as compared to the folded part 409 a of the first mesh member 407. Further, the end portion 417 a of the left-side area L₁ of the first mesh member 407 is also disposed on the inner side of the container 1 as compared to the folded part 409 b of the second mesh member 408.

In the process shown in FIGS. 17A to 17C, the areas and the like of the first and second mesh members 407 and 408 prepared are set as appropriate, thereby making it possible to dispose the end portion 416 a of the second mesh member 408 and the end portion 417 a of the second mesh member 408 as described above. With this structure, even if the wire is run in the end portion 416 a of the second mesh member 408 or in the end portion 417 a of the first mesh member 407, it is possible to prevent the run wire from getting into the bonding area S. As a result, the heat transport device 400 of this embodiment can be manufactured in a short time with good workability.

Fifth Embodiment

FIG. 18 is a schematic cross-sectional view showing a heat transport device according to a fifth embodiment. FIG. 19 is a schematic exploded perspective view showing the heat transport device of this embodiment. FIG. 18 shows the cross-sectional view in the case where the heat transport device of this embodiment is taken along a short-side direction.

As shown in FIGS. 18 and 19, a heat transport device 500 of this embodiment includes a lower plate member 503, a reinforcement member 519, and an upper plate member 504. The lower plate member 503 has a depressed portion 502. The reinforcement member 519 is bonded to the lower plate member 503, and the upper plate member 504 is bonded to the reinforcement member 519, thereby forming a container 501 of this embodiment. The reinforcement member 519 is made of oxygen-free copper, tough pitch copper, or a copper alloy, for example.

As shown in FIG. 18, in the reinforcement member 519, a plurality of reinforcement portions 520 are provided between a capillary member 505 and the upper plate member 504. The plurality of reinforcement portions 520 are arranged in the short-side direction of the container 501, and the reinforcement portions 520 are each extended in the long-side direction of the container 501. Gaps between the plurality of reinforcement portions 520 function as a gas-phase flow path 506′ in this embodiment. It should be noted that the capillary member 505 has the same structure as the capillary member 205 described in the second embodiment.

As shown in FIG. 19, the reinforcement member 519 has a plurality of through holes 521 that are formed extendedly in the long-side direction of the container 501. The plurality of through holes 521 are arranged in the short-side direction of the container 501. The through holes 521 function as the gas-phase flow path 506′ shown in FIG. 18, and the reinforcement portions 520 are respectively sandwiched between the through holes 521. The number of through holes 521, that is, the number of reinforcement portions 520 may be set as appropriate.

By providing the reinforcement portions 520 between the capillary member 505 and the upper plate member 504, the durability of the container 501 can be improved. For example, it is possible to prevent the container 501 from being deformed due to an internal pressure caused by the increase in inner temperature of the heat transport device 500. Further, for example, it is possible to prevent the container 501 from being deformed by a pressure when the working fluid is injected into the heat transport device 500 in a depressurized state.

Instead of the reinforcement member 519, the plurality of reinforcement portions 520 each having a shape of a cylinder or a polygonal column may be provided in an internal space 502′ of the container 501. Alternatively, by forming the plurality of reinforcement portions 520 on the upper plate member 504 and by bonding the upper plate member 504 and the lower plate member to each other, the reinforcements portions 520 may be provided in the internal space 502′. In this case, the reinforcement portions 520 are formed on the upper plate member 504 by an etching, a metal plating, a pressing process, a cutting process, or the like. In the case where the plurality of reinforcement portions 520 are formed on the upper plate member 504, it is possible to improve the durability of the heat transport device 500 at the time when a bending process is performed. In addition, the reinforcement member 519 is not used, so a component cost can be saved.

In the heat transport device 500 according to this embodiment, the capillary member 505 is set to have the same structure as the capillary member 205 described in the second embodiment. However, the structure of the capillary member according to another embodiment described above can also be applied thereto.

Sixth Embodiment

FIG. 20 is a schematic cross-sectional view showing a heat transport device according to a sixth embodiment. FIG. 20 shows the cross-sectional view in the case where the heat transport device of this embodiment is taken along a short-side direction.

As shown in FIG. 20, in a heat transport device 600 of this embodiment, a capillary member 605 is provided. The capillary member 605 has a thickness that is approximately equal to that of the internal space 2′ of the container 1. The capillary member 605 is formed by folding a second mesh member 608 having larger meshes so that a first mesh member 607 having smaller meshes is sandwiched therebetween. The way of folding the second mesh member 608 is similar to the way of folding the second mesh member 208 described in the second embodiment.

By providing the first and second mesh members 607 and 608 having a predetermined thickness, the thickness of the capillary member 605 is set to be almost the same as the thickness of the internal space 2′ of the container 1. Alternatively, by appropriately setting the height of the side wall 18 of the lower plate member 3, the thickness of the capillary member 605 and the thickness of the internal space 2′ (height of the side wall 18) may be set to be approximately equal to each other.

Since the thickness of the internal space 2′ of the container 1 is almost the same as the thickness of the capillary member 605 in the heat transport device 600, the capillary member 605 is provided in the entire internal space 2′ of the container 1 as shown in FIG. 20. With this structure, the durability of the container 1 can be improved, which can prevent the container 1 from being deformed. In addition, there is no need to provide another member for improving the durability of the container 1 in the internal space 2′, with the result that the component cost can be saved, and the heat transport device 600 can be manufactured in a short time with good workability.

Further, in this embodiment, the second mesh member 608 having the larger meshes functions as a gas-phase flow path 608′, and the first mesh member 607 having the smaller meshes functions as a liquid-phase flow path 607′. As described in the first embodiment, in the case where the mesh member is used as the gas-phase flow path, the use of the mesh member having the larger meshes makes the capillary radius rv of the gas-phase flow path larger. The use of the gas-phase flow path having the larger capillary radius rv increases the maximum heat transport amount Qmax. Accordingly, by using the second mesh member 608 having the larger meshes as the gas-phase flow path 608′, it is possible to improve the heat transport performance of the heat transport device 600.

It should be noted that in the first to fourth embodiments, the thickness of the capillary member is set to be approximately equal to the thickness of the internal space of the container, with the result that the same effect as in this embodiment can be obtained.

Seventh Embodiment

FIG. 21 is a schematic cross-sectional view showing a heat transport device according to a seventh embodiment. FIGS. 22A and 22B are diagrams showing a capillary member of this embodiment. FIG. 21 shows the cross-sectional view in the case where the heat transport device of this embodiment is taken along a short-side direction.

As shown in FIG. 21, in a heat transport device 700 of this embodiment, a capillary member 705 is provided. The capillary member 705 has a thickness that is approximately equal to the thickness of the internal space 2′ of the container 1. A second mesh member 708 of the capillary member 705 which has larger meshes functions as a gas-phase flow path 708′. In the second mesh member 708, a plurality of through holes 722 are formed.

As shown in FIG. 22A, the second mesh member 708 that is nearly twice as large as the internal space 2′ when viewed from above is prepared. The second mesh member 708 has the three areas of the right-side area R₂, the left-side area L₂, and a central area C₂. In the right-side area R₂ and the left-side area L₂, the plurality of through holes 722 are formed. The plurality of through holes 722 can be easily formed with a cutting die or the like. Further, in the central area C₂ of the second mesh member 708, a first mesh member 707 formed into almost the same shape as the internal space 2′ is placed. The first mesh member 707 includes a pair of end portions 717 a and 717 b opposed to each other in the short-side direction.

As shown in FIG. 22B, the second mesh member 208 is folded so that the first mesh member 207 is sandwiched. With this structure, the end portions 717 a and 717 b of the first mesh member 707 are covered with folded parts 709 a and 709 b of the second mesh member 708. The right-side area R₂ and the left-side area L₂ of the second mesh member 708, in which the plurality of through holes 722 are formed, are layered on the first mesh member 707.

By forming the plurality of through holes 722 in the second mesh member 708 serving as the gas-phase flow path 708′, the capillary radius rv of the gas-phase flow path 708′ is substantially increased. Thus, the maximum heat transport amount Qmax of the heat transport device 700 can be improved.

It should be noted that in the above embodiments, by forming the through holes in the second mesh member folded, the heat transport performance of the heat transport device can be improved. The through holes may be formed in the first mesh member sandwiched.

Eighth Embodiment

FIG. 23 is a schematic perspective view showing a heat transport device according to an eighth embodiment. FIGS. 24A to 24C are diagrams for explaining a method of manufacturing a heat transport device of this embodiment. FIGS. 24A to 24C show the cross-sectional views in the case where the heat transport device of this embodiment is taken along a short-side direction (along the line B-B).

As shown in FIG. 23, a heat transport device 800 of this embodiment includes a container 801 formed by folding one plate member 823. Typically, the plate member 823 is made of oxygen-free copper, tough pitch copper, or a copper alloy. However, the material is not limited to those, and metal other than copper, a resin, or another material having a higher thermal conductivity may be used as the plate member 823.

As shown in FIG. 24A, the flat plate member 823 is prepared. The plate member 823 has the bonding area S on both end portions thereof and is folded along a folded area U that is approximately the center of the plate member 823. To make it easy to fold the plate member 823, a groove, an opening, or the like may be formed in the folded area U.

As shown in FIG. 24B, when the plate member 823 is folded up to a predetermined angle, the capillary member 5 described in the first embodiment is placed in the plate member 823 folded. The capillary member 5 is placed in the plate member 823 so that the folded part 9 of the second mesh member 8 is disposed along the bonding area S of the plate member 823. Thus, the end portion 17 b of the first mesh member 7 and the pair of end portions 16 a and 16 b of the second mesh member 8 are opposed to the folded area U of the plate member 823. With this structure, it is possible to prevent the wire that runs at the end portions of the first and second mesh members 7 and 8 from getting into the bonding area S of the plate member 823.

The capillary member 5 may be placed on the plate member 823, before the folding of the plate member 823 is started. For example, the capillary member 5 may be placed on the plate member 823 so that the folded part 9 of the second mesh member 8 is disposed along the bonding area S on the left side in FIG. 24A.

As shown in FIG. 24C, the plate member 823 is further folded and bonded in the bonding area S by the diffusion bonding or the like. It should be noted that in this embodiment, the capillary member 5 of the first embodiment is used, but the capillary member according to another embodiment described above may be used instead.

In the heat transport device 800 of this embodiment, the container 801 is formed by folding the one plate member 823, with the result that the number of components is reduced, and the cost can be saved. In addition, in the case of a container constituted of a plurality of components, a predetermined positioning accuracy of the components is necessary. In contrast, in this embodiment, the high positioning accuracy is unnecessary.

Ninth Embodiment

FIG. 25 is a schematic perspective view showing a heat transport device according to a ninth embodiment. FIGS. 26A to 26C are diagrams for explaining a method of forming a capillary member of this embodiment.

As shown in FIG. 25, a heat transport device 900 of this embodiment includes a container 901 whose outline is an L-letter shape. The internal space of the container 901 also has an L-letter shape. Hereinafter, a description will be given on a method of forming the capillary member 905 of this embodiment, which is provided in the internal space having the L-letter shape.

As shown in FIG. 26A, a second mesh member 908 having the right-side area R₂ and the left-side area L₂ is prepared. The shape of the right-side area R₂ is the L-letter shape, which is approximately equal to the internal space of the container 901. The shape of the left-side area L₂ is an L-letter shape. The shape of the left-side area L₂ and the right-side area R₂ have a left-right symmetry in FIG. 26A.

As shown in FIG. 26B, on the right-side area R₂ of the second mesh member 908, a first mesh member 907 having the L-letter shape, which is approximately equal to the shape of the internal space of the container 901, is placed. The first mesh member 907 is superposed on the right-side area R₂ of the second mesh member 908. Further, an end portion 917 a of the first mesh member 907 is disposed on approximately the center of the second mesh member 908.

As shown in FIG. 26C, the second mesh member 908 is folded so as to cover the end portion 917 a of the first mesh member 907. Thus, the first mesh member 907 is sandwiched between the right-side area R₂ and the left-side area L₂ of the second mesh member 908, thereby forming the capillary member 905 having the L-letter shape according to this embodiment.

Here, another example of the capillary member 905 according to this embodiment will be described. FIGS. 27A and 27B are diagrams for explaining a method of forming a capillary member 955 of another example.

As shown in FIG. 27A, on a second mesh member 958 in which a plurality of turn-up areas O are formed, a first mesh member 957 having an L-letter shape, which is approximately equal to the shape of the internal space of the container 901, is placed. The plurality of turn-up areas O of the second mesh member 958 are provided so as to correspond to respective end portions 917 of the first mesh member 957. Between the turn-up areas O, cutoffs 924 or a slit 925 is formed.

As shown in FIG. 27B, the second mesh member 958 are folded so that the turn-up areas O of the second mesh member 958 are overlapped with the first mesh member 957. Thus, the first mesh member 957 is sandwiched therebetween, and the end portions 917 of the first mesh member 957 are covered with the turn-up areas O of the second mesh member 958.

As described above, in this embodiment, the shape of the second mesh member 908 (958) folded is set as appropriate in accordance with the shape of the container 901 of the heat transport device 900, thereby forming the turn-up areas O, for example. As a result, the capillary member 905 (955) having a desired shape can be formed.

Tenth Embodiment

FIG. 28 is a schematic perspective view showing an electronic apparatus according to a tenth embodiment. An electronic apparatus 150 of this embodiment includes the heat transport device according to the above embodiments. In this embodiment, a laptop PC (personal computer) is given as an example of the electronic apparatus 150.

The electronic apparatus 150 includes a main body 151 and a display unit 152 connected to the main body 151. The main body 151 and the display unit 152 are connected through a hinge 153, and the display unit 152 can be opened and closed (folded) with respect to the main body 151.

On the main body 151, a keyboard 154 and a touch pad 155 are provided. In the main body 151, a control circuit board (not shown) is provided on which an electrical circuit component 156 such as a CPU is mounted.

In the display unit 152, edge-light-type backlights 158 are provided. The backlights 158 emit light on a screen 157 of the display unit 152. As shown in FIG. 28, the backlights 158 are provided in an upper portion and a lower portion of the display unit 152. The backlights 158 are formed by disposing a plurality of white LEDs (light emitting diodes) on a copper plate, for example.

In this embodiment, a heat transport device 1000 is provided in the main body 151 and is brought into contact with the electronic circuit component 156. Alternatively, in the display unit 152, the heat transport device 1000 may be in contact with the copper plate that forms the backlights 158. In this case, as indicated by the broken lines of FIG. 28, a plurality of heat transport devices 1000 are provided in the display unit 152. The plurality of heat transport devices 1000 are mounted in a vertical position along the vertical direction of the display unit 152.

As described in the above embodiments, since the heat transport device 1000 has the high heat transport performance, heat generated in the electronic circuit component 156, the backlights 158, or the like can be quickly released to the outside of the electronic apparatus 150. Therefore, it is possible to prevent the electronic apparatus 150 from being broken down due to the heat generated in the electronic circuit component 156, the backlights 158, or the like. In addition, the heat transport device 1000 can make the internal temperature of the main body 151 or the display unit 152 uniform, which can prevent a low-temperature burn.

In this embodiment, the laptop PC is used as the example of the electronic apparatus 150. However, the electronic apparatus 150 is not limited to this. Examples of the electronic apparatus 150 include audiovisual equipment, a display apparatus, a projector, a gaming machine, a car navigation system, a robot apparatus, a PDA (personal digital assistant), an electronic dictionary, a camera, a cellular phone, and other electronics.

Modified Example

The present application is not limited to the above embodiments and can be variously modified without departing from the gist of the present application.

For example, in the above embodiments except the third embodiment described with reference to FIG. 13, a first mesh member having larger meshes and a second mesh member having smaller meshes may be used. In other words, the first mesh member having a smaller mesh number and the second mesh member having a larger mesh number may be used. Even in the case where such first and second mesh members are used, the same effect as the above embodiments can be obtained. For example, in the capillary member 605 according to the sixth embodiment described with reference to FIG. 20, the first mesh member 607 having the larger meshes may be set as the gas-phase flow path, and the second mesh member 608 having the smaller meshes may be set as the liquid-phase flow path.

As shown in FIG. 28, in the state where the display unit 152 is opened in the electronic apparatus 150, the heat transport devices 1000 provided to the backlight 158 on the lower side of the display unit 152 are in contact with the backlight 158 on the lower end portions of the heat transport devices. In this way, in the case where the heat source is in contact with the lower end portions of the heat transport devices vertically mounted, the heat transport devices are in a bottom-heat mode. In this case, the movement of the liquid-phase working fluid is urged by the gravity.

On the other hand, in the case where the heat source is in contact with the upper end portions of the heat transport device vertically mounted, the heat transport device is in a top-heat mode. In this case, the liquid-phase working fluid is moved against the gravity, so a high capillary force has to be applied to the liquid-phase working fluid.

As described above, depending on the orientation of the heat transport device mounted, the contact position with the heat source, or the like, a demanded feature of the heat transport device varies. The mesh numbers of the first and second mesh members only have to be selected as appropriate in accordance with the demanded feature of the heat transport device in consideration of whether to increase the capillary force that is applied to the liquid-phase working fluid or whether to increase the size of the gas-phase flow path of the gas-phase working fluid, for example.

FIGS. 29A, 29B, 30A, and 30B are diagrams showing modified examples of the heat transport device 100 according to the first embodiment. In the heat transport device 100, a capillary member 105 is formed by folding one mesh member 107. As shown in FIGS. 29 and 30, the way of folding the mesh member 107 may be set as appropriate.

By folding the one mesh member 107 as described above, the capillary member 105 is allowed to occupy the larger part of the internal space 2′ of the container 1. With this structure, the heat transport efficiency can be improved. Further, a positioning operation at the time when a plurality of mesh members are layered is unnecessary, improving the workability in the manufacture of the heat transport device 100. Furthermore, it is possible to prevent a wire of the mesh member from getting into the bonding area S of the container 1, with the result that the heat transport device 100 having the high heat transport performance can be manufactured in a short time with good workability.

It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims. 

1. A heat transport device, comprising: a working fluid to transport heat by performing a phase change; a capillary member to apply a capillary force to the working fluid, the capillary member including a first mesh member having a mesh of a first size and a second mesh member having a mesh of a second size different from the first size, the second mesh member being folded so that the first mesh member is sandwiched; and a container to contain the working fluid and the capillary member.
 2. The heat transport device according to claim 1, wherein the first mesh member has an end portion, and wherein the second mesh member is folded to cover the end portion.
 3. The heat transport device according to claim 2, wherein the first mesh member has a pair of end portions that are opposed to each other, and wherein the second mesh member is folded to cover the pair of end portions.
 4. The heat transport device according to claim 3, wherein the first size is smaller than the second size.
 5. The heat transport device according to claim 4, further comprising: a liquid-phase flow path through which the working fluid in a liquid phase passes; and a gas-phase flow path through which the working fluid in a gas phase passes, wherein the container includes an internal space having a thickness that is equal to a thickness of the capillary member, and wherein the capillary member includes the first mesh member and the second mesh member, the first mesh member serving as the liquid-phase flow path, the second mesh member serving as the gas-phase flow path.
 6. The heat transport device according to claim 1, wherein the first mesh member and the second mesh member are alternately folded to be sandwiched therebetween.
 7. The heat transport device according to claim 2, wherein the container includes a first member and a second member that are bonded to each other, and wherein the capillary member is contained in the container so that a folded part of the second mesh member is disposed along a bonding area of the first and second members.
 8. The heat transport device according to claim 2, wherein the container includes one plate member that is folded and bonded to form the container, and wherein the capillary member is contained in the container so that a folded part of the second mesh member is disposed along a bonding area of the plate member.
 9. A heat transport device, comprising: a working fluid to transport heat by performing a phase change; a capillary member to apply a capillary force to the working fluid, the capillary member including a first mesh member having meshes arranged in a first direction and a second mesh member having meshes arranged in a second direction different from the first direction, the second mesh member being folded so that the first mesh member is sandwiched; and a container to contain the working fluid and the capillary member.
 10. A method of manufacturing a heat transport device, comprising: forming a capillary member used for a heat transport device by folding a second mesh member to cause a first mesh member to be sandwiched and cover an end portion of the first mesh member, the first mesh member having a mesh of a first size, the second mesh member having a mesh of a second size different from the first size; placing the capillary member on a first member that constitutes a container of the heat transport device so that a folded part of the second mesh member is disposed along a bonding area of the first member; and forming the container that contains the capillary member by bonding a second member that constitutes the container to the bonding area of the first member.
 11. A method of manufacturing a heat transport device, comprising: forming a capillary member used for a heat transport device by folding a second mesh member to cause a first mesh member to be sandwiched and cover a pair of end portions of the first mesh member; placing the capillary member on a first member that constitutes a container of the heat transport device so that a folded part of the second mesh member is disposed along a bonding area of the first member; and forming the container that contains the capillary member by bonding a second member that constitutes the container to the bonding area of the first member.
 12. A method of manufacturing a heat transport device, comprising: forming a capillary member used for a heat transport device by folding a second mesh member to cause a first mesh member to be sandwiched and cover an end portion of the first mesh member, the first mesh member having a mesh of a first size, the second mesh member having a mesh of a second size different from the first size; placing the capillary member on one plate member that constitutes a container of the heat transport device so that a folded part of the second mesh member is disposed along a bonding area of the plate member; and forming the container that contains the capillary member by folding and bonding the plate member to the bonding area.
 13. An electronic apparatus, comprising: a heat source; and a heat transport device including a working fluid to transport heat by performing a phase change, a capillary member to apply a capillary force to the working fluid, the capillary member including a first mesh member having a mesh of a first size and a second mesh member having a mesh of a second size different from the first size, the second mesh member being folded so that the first mesh member is sandwiched, and a container to contain the working fluid and the capillary member, the container being connected to the heat source. 